Geometry terms
•Point – exact location in space .A
Symbol Point A
•Line – continuous set of points in a straight line path. Co-linear (points or a straight line of points ( ↔) non-co-linear not on a line
Symbol ↔
•Line segment – a line with two end points
Symbol −
•Ray – part of line with one end point.
Symbol →
•Angle is a figure formed by two rays with a common endpoint. The common end point is called the vertex.
Symbol angle B, angle ABC,
•Plane is a flat two-dimensional surface that extends infinitely in all directions. Co-planar are points that lie on the same plane.
Symbols plane xyz
•Intersecting lines are two lines that cross at exactly one point
•Perpendicular lines are 2 intersecting lines that form a right angle ( 90◦ angle)
•Parallel lines are lines that do not intersect and lie on the same planes.
•Skew lines are that lie on different planes and are not intersecting or parallel
Angles
•Acute angles are less than 90⁰
•Right angles equal 90⁰
•Obtuse angles are greater than 90⁰ but less than 180⁰.
•Straight angles are equal to 180⁰
•Reflex angles are greater than 180⁰ but less than 360⁰
•Interior points are all points in the plane between the two rays
Angle pairs
•Complementary angles are two angles with a sums of 90⁰
•Supplementary angles are two angles with a sum of 180⁰
•Adjacent angles have a common side and vertex but no common interior points (interior points do not overlap)
•Vertical angles are a pair of opposite angles that are formed by two intersecting lines.
•The sum of all triangle angles are 180⁰
Parallel line and Transversals
•Transversal is a line that intersects two parallel lines.
•Interior angles: angles inside the parallel lines
•Exterior angles: angles outside the parallel lines
•Corresponding angles: angles are congruent ; one interior and one exterior that are nonadjacent; same side of transversal line
•Alternate interior angles: angles are congruent; nonadjacent interior angles on opposite sides of transversal line
•Alternate exterior angles: angles are congruent; nonadjacent exterior angles on opposite sides of transversal line
Polygons
Polygons
•A closed Figure
•Has 3 or more sides
•Each side is a line segment ( they must meet only at their endpoints)
•Regular Polygon all sides and angles are congruent
•Triangle: a polygon having 3 side and 3 vertices
Quadrilaterals
•Square: A quadrilateral with all sides congruent and parallel with 4 right angles
•Rhombus: A quadrilateral with all sides congruent and opposite sides are parallel.
•Rectangle: A quadrilateral with 4 right angles and opposite are congruent and parallel
• Parallelogram: A quadrilateral with opposite sides congruent and parallel
•Trapezoid: A quadrilateral having only one pair of opposite sides parallel
*Kite: A quadrilateral with two pairs of adjacent sides that are congruent.
•Pentagon: 5 side
•Hexagon: 6 sides
•Heptagon: 7 sides
•Octagon: 8 sides
•Nonagon: 9 sides
•Decagon: 10 sides
Triangle
•Acute Triangle : A triangle with each angle less than 90⁰
•Right Triangle: A triangle with one angle that measures exactly 90⁰
•Obtuse Triangle: A triangle with one angle greater than 90⁰
•Equilateral Triangle: A triangle having 3 sides of equal length and 3 angles equal in degrees
•Isosceles Triangle: A triangle having 2 sides equal in length
•Scalene Triangle: A triangle with all 3 sides unequal in length
Circles
*Circle is a set of points in a plane, all of which are the same distance from a given point called the center.
*Radius is a line segment from the center of a circle to a point on the circle [formula of a radius is diameter divided by 2]
*Central angle has its vertex at the center of the circle
*Inscribed Angle is an angle whose vertex is on the circle and whose sides intersect the circle at other points.
*Chord is a line segment with its endpoints on the circle
*Tangent to a circle is a line in the plane of the circle
*Secant is a line that intersects a circle at two points.
*Diameter is a chord that passes through the center of a circle [formula of a diameter is 2 times the radius]
*Arc is a part of a circle, with all of its points on the circle
Semicircle is an arc that connects the endpoints of a diameter which measures 180 degrees
Minor Arc is an arc with a measure less than 180 degree
Major Arc is an arc with a measure greater than 180 degree